A flat-plate-shaped device under test such as an integrated circuit or a display board undergoes an electrical test with use of an electrical connecting apparatus such as a probe card. In the electrical test, the device under test is thrust by contactors of the electrical connecting apparatus at its electrodes and is powered in such a state.
As one of the electrical connecting apparatuses of this kind, there is an art of using a flexible circuit board having a flexible sheet-like member such as an FPC in which a flexible electrical insulating sheet is provided with a plurality of wires, and a plurality of contactors soldered to the respective wires of this sheet-like member (Patent Document 1).
Patent Document 1: Japanese Unexamined Patent Publication No. 2002-311049, which is incorporated by reference.
In the above conventional art, each contactor comprises a pedestal portion coupled with the wire at one end portion, an arm portion extending from the other end of the pedestal portion in the longitudinal direction of the wire, and a probe tip portion protruded from the tip end of the arm portion to a side opposite the pedestal portion. The arm portion and the probe tip portion act as a main body portion that is elastically deformed substantially at the arm portion when the tip end of the probe tip portion, that is, the probe tip, is thrust to an electrode of a device under test.
The circuit board using such contactors is attached to a support board such as a wiring board by an attachment device so that the probe tip portions can be directed to the device under test, thus to be assembled into an electrical connecting apparatus.
The attachment device comprises a plate-shaped member arranged on the upper surface of the support board, a ring-shaped member arranged in a step portion directing downward provided at the center of the support board so as to be located at the step portion, a plate spring screwed on the lower side of the ring-shaped member, and a block having at least an attachment surface on the lower side, located on the lower side of the plate spring in a state where the attachment surface is protruded in the downward direction of the support board, and screwed in the ring-shaped member.
The plate-shaped member is attached to the support board by a plurality of attachment screws penetrating the plate-shaped member and the support board in the up-down direction and screwed in the ring-shaped member and attaches the ring-shaped member to the support board. The plate spring is kept in parallel with the support board.
The aforementioned circuit board is bonded to the attachment surface of the block at a contactor area at which the contactors are arranged and is attached to the lower surface of the support board by a ring-shaped spring holder and a plurality of locking screws at an outermost circumferential portion of an outer area surrounding this contactor area.
After the above electrical connecting apparatus is attached to a testing apparatus such as a prober, the probe tip of each contactor is thrust to the electrode of the device under test so that predetermined probe pressure acts on the electrode and the probe tip, and a desired contactor is powered in a state where predetermined overdriving acts on each contactor. By doing so, an electrical test is conducted.
When an imaginal probe tip surface formed by all the probe tips is inclined to the support board or the testing apparatus (device under test), the arm portion of each contactor and the plate spring are elastically deformed since the probe tip is thrust to the device under test. Accordingly, the contactor area and the probe tip surface are automatically compensated to be parallel to the support board.
However, in the conventional electrical connecting apparatus, since the plate spring is kept in parallel with the support board in a state where the probe tip of each contactor is not thrust to the electrode of the device under test, the probe pressure and the overdriving amount are proportional to each other.
Thus, in the conventional electrical connecting apparatus, the damage given to the contactor and the electrode increases when the overdriving amount is large, while the probe pressure may be too small to obtain a good electrical contacting state between the probe tip and the electrode when the overdriving amount is small.